Hi Ken -- I replied to this on another forum; where your question also appears. In case you haven't wandered back there yet; here's my response:
It would help if you knew what kind and how old it is. Apparently, the day of citrus growing for the backyard gardener won't be for many more years as Florida now has that fatal disease "greening". Citrus greening is one of the most serious citrus plant diseases in the world. It is also known as Huanglongbing (HLB) or yellow dragon disease. Once a tree is infected, there is no cure. Unlike the canker that hit our citrus some years ago; this makes the fruit unpalatable and also kills the tree.
I have one citrus tree growing in the ground; a Meyer lemon. Those lemons are huge and juicy. However all the fruit is growing on the lower limbs of the tree - nothing on the top branches. I don't know why and neither do my gardening friends. Very odd.
I have a Key Lime tree in a huge pot, and it's loaded with blossoms at the moment (for the second year); also a Persian lime (also in a huge pot) which produced quite a bit of fruit. I actually made a few key lime pies this past year - something I'd never done before; just wonderful. I had some English friends staying with me last weekend and served it for dessert -- they raved about the pie.
Back to your citrus tree; it would be good if you could identify it -- I'm pretty sure you don't need another citrus tree to encourage blooming and fruiting (as you would with Papaya). Just get a good citrus fertilizer and apply at the right time for your area. I'm sure you won't have to worry about greening for a few years yet.
